The present invention relates to a method of stabilizing a fluorine-containing acid amplifier.
With the recent development of digital devices such as computers, it has become common to process an enormous amount of operational data or two- or three-dimensional image data. There is a need to provide large-capacity high-speed memories and high-performance microprocessors for quick processing of such enormous information. Further, the processing power required of the digital devices is estimated to increase more and more as the broadband spreads with the development of network systems such as the Internet.
In order to meet this need, various devices such as semiconductor devices are required to achieve higher density and higher integration. The requirements for photolithography processes, which enable fine patterning, are particularly becoming more stringent year by year. For example, photolithography process using ArF excimer laser radiation (wavelength: 193 nm) has been put into use in response to the requirement for patterning techniques with a minimum line width of 0.13 μm or less for production of 1 Gbit or higher-capacity DRAMs. The development of photolithography process using extreme ultraviolet (EUV) radiation has also been pursued for finer patterning.
For the purpose of improving line edge roughness in these wavelength regions, studies of additives for photoresists such as photoacid generators had been eagerly made. In extreme ultraviolet (EUV) region, however, it is sometimes difficult to sufficiently improve line edge roughness only by photoacid generators because of poor energy from light source. In response to the increasing requirements for finer patterning by photoresist, there have been reported such fluorine-containing acid amplifiers as to form a secondary acid from acid generated by a photoacid generator thereby allowing improvement of line edge roughness of photoresist pattern (Non-Patent Publications 1 and 2).